C2- and C4-position 17beta-estradiol metabolites and their relation to breast cancer: [review]

C2- and C4-position 17beta-estradiol metabolites play an important role in breast carcinogenesis. 2-Hydroxyestradiol and 4-hydroxyestradiol are implicated in tumorigenesis via two pathways. These pathways entail increased cell proliferation and the formation of reactive oxygen species that trigger an increase in the likelihood of deoxyribonucleic acid mutations. 2-Methoxyestradiol, a 17beta-estradiol metabolite, however, causes induction of apoptosis in transformed and tumor cells; thus exhibiting an antiproliferative effect on tumor growth. The 4-hydroxyestradiol:2-methoxyestradiol and 2-hydroxyestradiol:2-methoxyestradiol ratios therefore ought to be taken into account as possible indicators of carcinogenesis.

C2- and C4-position 17beta-estradiol metabolites and their relation to breast cancer: [review]

C2- and C4-position 17beta-estradiol metabolites play an important role in breast carcinogenesis. 2-Hydroxyestradiol and 4-hydroxyestradiol are implicated in tumorigenesis via two pathways. These pathways entail increased cell proliferation and the formation of reactive oxygen species that trigger an increase in the likelihood of deoxyribonucleic acid mutations. 2-Methoxyestradiol, a 17beta-estradiol metabolite, however, causes induction of apoptosis in transformed and tumor cells; thus exhibiting an antiproliferative effect on tumor growth. The 4-hydroxyestradiol:2-methoxyestradiol and 2-hydroxyestradiol:2-methoxyestradiol ratios therefore ought to be taken into account as possible indicators of carcinogenesis.(AU)

In vitro effects of Sutherlandia frutescens water extracts on cell numbers, morphology, cell cycle progression and cell death in a tumorigenic and a non-tumorigenic epithelial breast cell line.

Sutherlandia frutescens is a South African herb traditionally used for internal cancers, diabetes, a variety of inflammatory conditions and recently to improve the overall health in cancer and HIV/AIDS patients. The in vitro effects of S. frutescens extracts were evaluated on cell numbers, morphology, cell cycle progression and cell death. Dose-dependent studies (2-10 mg/ml) revealed a decrease in malignant cell numbers when compared to their controls. S. frutescens extracts (10 mg/ml) decreased cell growth in a statistically significantly manner to 26% and 49% (P<0.001) in human breast adenocarcinoma (MCF-7) and human non-tumorigenic epithelial mammary gland cells (MCF-12A) respectively after 72 h of exposure. Cell density was significantly compromised and hypercondensed chromatin, cytoplasmic shrinking, membrane blebbing and apoptotic bodies were more pronounced in the MCF-7 cell line. Both S. frutescens-treated cell lines exhibited and increased tendency for acridine orange staining, suggesting increased lysosomal and/or autophagy activity. Flow cytometry showed an increase in the sub G(1) apoptotic fraction and an S phase arrest in both the 5 mg/ml and 10 mg/ml S. frutescens-treated cells. S. frutescens induced an increase in apoptosis in both cell lines as detected by Annexin V and propidium iodide flow cytometric measurement. At 10 mg/ml, late stages of apoptosis were more prominent in MCF-7 S. frutescens-treated cells when compared to the MCF-12A cells. Transmission electron microscopy revealed hallmarks of increased vacuolarization and hypercondensed chromatin, suggesting autophagic and apoptotic processes. The preliminary study demonstrates that S. frutescens water extracts exert a differential action mechanism in non-tumorigenic MCF-12A cells when compared to tumorigenic MCF-7 cells, warranting future studies on this multi-purpose medicinal plant in southern Africa.

In vitro effects of 2-methoxyestradiol on cell numbers, morphology, cell cycle progression, and apoptosis induction in oesophageal carcinoma cells.

The influence of 2-methoxyestradiol (2-ME) was investigated on cell numbers, morphology, cell cycle progression, and apoptosis induction in an oesophageal carcinoma cell line (WHCO3). Dose-dependent studies (1 x 10(-9)M-1 x 10(-6)M) revealed that 2-ME significantly reduced cell numbers to 60% in WHCO3 after 72 h of exposure at a concentration of 1 x 10(-6)M compared to vehicle-treated cells. Morphological studies entailing light-, fluorescent-, as well as transmission electron microscopy (TEM) confirmed 2-ME's antimitotic effects. These results indicated hallmarks of apoptosis including cell shrinkage, hypercondensation of chromatin, cell membrane blebbing, and apoptotic bodies in treated cells. Flow cytometric analyses demonstrated an increase in the G(2)/M-phase after 2-ME exposure; thus preventing cells from proceeding through the cell cycle. beta-tubulin immunofluorescence revealed that 2-ME caused spindle disruption. In addition, increased expression of death receptor 5 protein was observed further supporting the proposed mechanism of apoptosis induction via the extrinsic pathway in 2-ME-exposed oesophageal carcinoma cells.

C2- and C4-position 17beta-estradiol metabolites and their relation to breast cancer.

C2- and C4-position 17beta-estradiol metabolites play an important role in breast carcinogenesis. 2-Hydroxyestradiol and 4-hydroxyestradiol are implicated in tumorigenesis via two pathways. These pathways entail increased cell proliferation and the formation of reactive oxygen species that trigger an increase in the likelihood of deoxyribonucleic acid mutations. 2-Methoxyestradiol, a 17beta-estradiol metabolite, however, causes induction of apoptosis in transformed and tumor cells; thus exhibiting an antiproliferative effect on tumor growth. The 4-hydroxyestradiol:2-methoxyestradiol and 2-hydroxyestradiol:2-methoxyestradiol ratios therefore ought to be taken into account as possible indicators of carcinogenesis.

In vitro effects of 2-methoxyestradiol on MCF-12A and MCF-7 cell growth, morphology and mitotic spindle formation.

The influence of 2-methoxyestradiol (2ME) was investigated on cell growth, morphology and spindle formation in a tumorigenic (MCF-7) and non-tumorigenic (MCF-12A) epithelial breast cell line. Inhibition of cell growth was more pronounced in the MCF-7 cells compared to the MCF-12A cells following 2ME treatment. Dose-dependent studies (10(-5)-10(-9) M) revealed that 10(-6) M 2ME inhibited cell growth by 44% in MCF-12A cells and by 84% in MCF-7 cells (p-value < 0.05). 2ME-treated MCF-7 cells showed abnormal metaphase cells, membrane blebbing, apoptotic cells and disrupted spindle formation. These observations were either absent or less prominent in MCF-12A cells. 2ME had no effect on the length of the cell cycle between S-phase and the time a mitotic peak was reached in either cell line but MCF-7 cells were blocked in mitosis with no statistically significant alterations in the phosphorylation status of Cdc25C. Nevertheless, Cdc2 activity was significantly increased in MCF-7 cells compared to MCF-12A cells (p-value < 0.05). The results indicate that 2ME disrupts mitotic spindle formation and enhances Cdc2 kinase activity, leading to persistence of the spindle checkpoint and thus prolonged metaphase arrest that may result in the induction of apoptosis. The tumorigenic MCF-7 cells were especially sensitive to 2ME treatment compared to the normal MCF-12A cells. Therefore, differential mechanism(s) of growth inhibition are evident between the normal and tumorigenic cells.

2-methoxyestradiol strongly inhibits human uterine sarcomatous cell growth.

OBJECTIVES: The objective was to test the hypothesis that uterine sarcomatous cells are hormone-sensitive. We included 2-methoxyestradiol, an endogenous metabolite of estradiol with antiproliferative properties. METHODS: Proliferation assays assessed the effects of estradiol, progesterone, tamoxifen, raloxifen, [D-Trp(6)]leuteinizing hormone-releasing hormone (LHRH), ICI 182,780 (faslodex or fulvestrant), and 2-methoxyestradiol on cell growth of a cell line derived from uterine carcinosarcoma, but consisting solely of mesenchymal cells (SK-UT-1). Morphological changes of SK-UT-1 cells after exposure to 2-methoxyestradiol were evaluated and fluorescence immunohistochemistry for tubulin was used to detect changes in the mitotic spindle. Flow cytometry was used to assess the influence of 2-methoxyestradiol on the SK-UT-1 cell cycle as well as the role of p53 in apoptosis. RESULTS: Cell proliferation analysis revealed that SK-UT-1 cells were stimulated by progesterone, tamoxifen, and [D-Trp(6)]LHRH. Cells were insensitive to estradiol, raloxifen, and ICI 182,780. Inhibition occurred after exposure to 2-methoxyestradiol and was accompanied by a threefold increase in the G2/M population, with a concomitant decrease in the G1 population, as shown by cell cycle analysis. SK-UT-1 cells exposed to 2-methoxyestradiol showed morphological changes indicative of apoptosis. Examination of signaling pathways that mediate 2-methoxyestradiol-induced apoptosis showed p53-independent growth inhibition. The inhibition of SK-UT-1 cell growth by arresting the cells during G2/M progression could be attributed to interference with the microtubule system, as determined by fluorescence immunohistochemistry. CONCLUSIONS: The stimulatory effect of progesterone, tamoxifen, and [D-Trp(6)]LHRH suggests that uterine sarcomatous cells are hormone-sensitive. Our finding that 2-methoxyestradiol-mediated growth inhibition of uterine sarcomatous cells occurred in a p53-independent manner may have considerable clinical significance. The inadequate armature against uterine sarcomas and the limited toxicity of 2-methoxyestradiol may render these observations especially important.

The effects of prostaglandin A2 on cell growth, cell cycle status and apoptosis induction in HeLa and MCF-7 cells.

The effects of 20 microg/ml exogenous prostaglandin A(2) (PGA(2)) were evaluated on cell numbers in HeLa (human epithelial cervix carcinoma) and MCF-7 (human breast carcinoma) cells. In HeLa cells, PGA(2) reduced cell numbers significantly to 75% after 24 h (P < 0.05) and exposure of 48 h decreased cell numbers to 61% (P < 0.05) of the control. In MCF-7 cells, PGA(2) significantly reduced cell numbers to 48% after 24 h and to 20% after 48 h, compared to vehicle-treated control cells (P < 0.05). The anti-mitogenic effects were confirmed by morphological studies conducted after 48 h of exposure to PGA(2), when optimal effects were observed. HeLa and MCF-7 cells exposed to PGA(2), showed chromatin aggregation, cell membrane blebbing and uneven distribution of chromosomes. Cell cycle progression analysis of HeLa and MCF-7 cells, showed an increase in DNA content preceding the G(0)/G(1) peak after 48 h of exposure, which is indicative of apoptotic body formation.